title: Concepts and mechanisms: crossing host barriers.
abstract: The human body is bordered by the skin and mucosa, which are the cellular barriers that define the frontier between the internal milieu and the external nonsterile environment. Additional cellular barriers, such as the placental and the blood-brain barriers, define protected niches within the host. In addition to their physiological roles, these host barriers provide both physical and immune defense against microbial infection. Yet, many pathogens have evolved elaborated mechanisms to target this line of defense, resulting in a microbial invasion of cells constitutive of host barriers, disruption of barrier integrity, and systemic dissemination and invasion of deeper tissues. Here we review representative examples of microbial interactions with human barriers, including the intestinal, placental, and blood-brain barriers, and discuss how these microbes adhere to, invade, breach, or compromise these barriers.
authors.affiliation: Department of Biology and Center for Microbial Sciences, San Diego State University, San Diego, California 92182, USA. kdoran@mail.sdsu.edu
authors.forename: Kelly S
authors.initials: KS
authors.lastname: Doran
authors.forename: Anirban
authors.initials: A
authors.lastname: Banerjee
authors.forename: Olivier
authors.initials: O
authors.lastname: Disson
authors.forename: Marc
authors.initials: M
authors.lastname: Lecuit
mesh_terms: D000818:Animals; D001419:Bacteria / Q000472:pathogenicity*; D001422:Bacterial Adhesion / Q000502:physiology; D018988:Bacterial Translocation / Q000502:physiology; D001812:Blood-Brain Barrier / Q000382:microbiology*; D005260:Female; D054884:Host-Pathogen Interactions / Q000502:physiology; D006801:Humans; D007249:Inflammation / Q000382:microbiology; D007413:Intestinal Mucosa / Q000382:microbiology*; D010271:Parasites / Q000472:pathogenicity*; D010587:Phagocytosis / Q000502:physiology; D010920:Placenta / Q000382:microbiology; D011247:Pregnancy; D012867:Skin / Q000382:microbiology*; D014780:Viruses / Q000472:pathogenicity*